My dad had a lovely Crepe Myrtle Tree so when I saw dwarf ones were available I bought one and planted it in a big concrete pot. It died. I dug it out and discovered tree roots had invaded the pot and starved the poor tree of water and nutrients. I decided to have another go with a big metal tub which I placed on weed mat. The new Crepe Myrtle died. Today I dug that out and emptied the tub only to find the central hole completely clogged with roots which have grown up through the weed mat. From now on I’m going to make sure that all my pots sit either off the ground or on some solid base!